Final Results From The Betaseron® (interferon beta -1b) Pregnancy Registry

Background: Women with multiple sclerosis (MS) are typically diagnosed between 20 and 40 years of age, when their childbearing potential is greatest. There are insufficient data on the potential risks of fetal exposure to interferon beta-1b (Betaseron®) to guide patient counseling and decision making by women who are pregnant or wish to become pregnant during treatment.

Objectives: The Betaseron Pregnancy Registry was initiated by Bayer HealthCare Pharmaceuticals in 2006 to monitor rates of birth defects, spontaneous abortions (SABs), and other negative pregnancy outcomes for women exposed to interferon beta-1b during pregnancy.

Methods: This prospective, observational registry enrolled women exposed to interferon beta-1b around the time of conception and/or during pregnancy but prior to prenatal screening that identified fetal abnormalities. Follow-up continued through pregnancy and beyond, with infants monitored through their 4-month pediatrician visit. Outcomes were compared with established rates from the Metropolitan Atlanta Congenital Defects Program and the National Center for Health Statistics.

Results: Between April 24, 2006 and July 31, 2011, 99 pregnant women were enrolled prospectively. 96 (97.0%) had known pregnancy outcomes, including 74 (77.1%) with pediatric follow-up. Initial exposure to interferon beta-1b occurred during the first trimester for 95 pregnancies and in the third trimester for 1 pregnancy. The 96 pregnancies resulted in 99 birth outcomes (3 sets of twins), including 86 (86.9%) live births, 11 (11.1%) SABs, and 2 (2.0%) stillbirths. Birth defects were reported in 5 (5.1%) cases: trisomy 21, hemangiomas, cardiovascular abnormalities (patent foramen ovale, patent ductus arteriousus, ventriculoseptal defect) and hip dysplasia, abnormal head shape without craniosynostosis, and polydactyly (postaxial hand). During pregnancy, the mother of 1 stillborn baby had hypertension, obesity, folliculitis, an MS attack, and oligohydramnios, and the other had HPV infection, migraines, fibroids, depression, high cholesterol, iron deficiency, antiphospholipid antibody, and incompetent cervix. Rates of birth defects (5.8%) and SAB (11.5%) were not significantly different from established rates (2.78% and 16%, respectively).

Conclusions: Definitive conclusions cannot be drawn from these data due to the small sample size; however, there was no pattern to suggest increased negative outcomes with interferon beta-1b.  Continued monitoring is recommended.